Various systems have been developed for thermal cutting, sealing and welding of tissues. An example of a novel system which combines thermal cutting, sealing and welding with tissue grasping and manipulation capabilities is provided in U.S. Pat. No. 6,626,901, owned by The Trustees of Columbia University in the City of New York.
When performing thermal cutting, sealing or welding of tissue, very precise temperatures and exposure times are required. This is due to the fact that tissues can easily be damaged by inadvertently high thermal exposure levels. Moreover, tissue sealing is accomplished at lower temperature levels than tissue cutting; and the boundary between such sealing and cutting temperatures is hard to precisely define. This is especially true when mechanical pressure is also applied to the tissue when thermally sealing or cutting the tissue. In addition, when thermally heating tissue, some portions of the tissue may be heated to a cutting temperature, whereas tissue located farther from the heat source may only be heated to a sealing temperature. Consequently, any system that is flexible enough to perform both thermal sealing and thermal cutting of tissue requires a well controlled heating system.